Generally, a power relay assembly is a power cutoff apparatus configured to connect and disconnect a power connected to a motor from a battery of an electrical vehicle and a hybrid vehicle using a power control unit (PCU), which is a core component serving as a main gate for supplying a power. Further, the power relay assembly serves as a safety device for completely cutting off power supply in the occurrence of a system error or in a state of repair (maintenance), etc., thereby protecting an electric vehicle/hybrid vehicle.
Such power relay assembly includes a high-voltage relay such as a pre-charging relay (450V, 10 A or more) and a main relay (450V, 100˜150 A or more), a high voltage/large current bus bar for wire connection with a battery/inverter, a terminal, etc. Among such components, a core component is a high voltage relay serving to connect or disconnect a high voltage/large current. A mechanical relay structure, where special gas such as H2 has been injected in a sealed manner for prevention of spark which can occur at a contact of the relay, has been mainly used as the high voltage relay.
However, such high voltage relay increases the entire weight of the power relay assembly, because it is heavy due to its special gas.
Further, the high voltage relay has a complicated mechanical structure, and has expensive components because the material cost of the components is high. This may cause the cost of the power relay assembly to be increased.